what do you count as official day 1

Erica

of AF?! CD 15 && had some brown dark red spotting while wiping this morning an hour later it's gone ... could be implantation could be AF. if I get a full Flo tomorrow would I count today as CD 1 or tomorrow as CD 1?? starting Clomid this round so I want every thing to be on the money !!! thanks ladies . I think starting the Clomid if this is AF is the only thing keeping me happy about another period!!